1. Field of the Invention
The present invention generally relates to a display, in particular, to a liquid crystal display (LCD).
2. Description of Related Art
Thanks to the advantages of high definition, desirable space utilization efficiency, low power consumption, and no radiation etc., the LCD has gradually become the main stream of the displays. As the prevailing of the LCD, one of the important indexes to be considered by the consumer when purchasing the LCD is high color reproduction. Recently, in order to meet the consumers' requirements, various LCDs adopting the high color reproduction technique have successively appeared on the market.
The LCD is mainly constituted by a liquid crystal display panel and a backlight module for providing a light source to the liquid crystal display panel, in which the liquid crystal display panel includes, for example, an active device array substrate, a color filter substrate, and a liquid crystal layer sandwiched therebetween, and the color filter substrate has a red filter layer, a green filter layer, and a blue filter layer. Generally, the light source in the backlight module may adopt a cold-cathode fluorescent lamp (CCFL), a light emitting diode (LED), or other types of light sources. Taking the CCFL as a white light source in the backlight module for example, currently, the color saturation NTSC ratio of the LCD substantially reaches a level from about 70% to 75%, in which the color saturation NTSC ratio is used to evaluate the color saturation according to the standard issued by the National Television System Committee (NTSC). In addition, for those of ordinary skill in the art, when the red saturation, green saturation, and blue saturation of the LCD are adjusted, the Adobe specification is generally taken as a reference for color adjustment. According to the Adobe specification, in CIE1931 chromaticity coordinate diagram, the red chromaticity coordinates, green chromaticity coordinates, and blue chromaticity coordinates are respectively represented as red specification (Rx, Ry)=(0.640, 0.330), green specification (Gx, Gy)=(0.210, 0.710), and blue specification (Bx, By)=(0.150, 0.060).
In order to improve the color saturation of the LCD, various techniques have successively been proposed, among which one conventional art uses a CCFL together with a red LED in a backlight module to adjust the color saturation. FIG. 1A is a schematic view of CIE1931 chromaticity coordinate diagram of the LCD. Referring to FIG. 1A, the representation of the LCD 10 at green still has a certain distance from the green color coordinates of the Adobe specification. In other words, the green color saturation representation of the LCD 10 is not so desirable, and as a result, the whole color saturation of the LCD 10 is not ideal.
Accordingly, US Patent Publication US20060132679 provides another LCD 20 using CCFL as the backlight module. FIG. 1B is a schematic view of CIE1931 chromaticity coordinates of the conventional LCD. Referring to FIG. 1B, although the representation of the LCD 20 on the green color saturation is better than that of the LCD 10 in FIG. 1, the representation of the LCD 20 on the red color is less desirable, such that the overall color saturation representation of the LCD 20 still requires to be improved.